US 3603876 A
Description (OCR text may contain errors)
United States Patent  Inventor Reed H. Grundy Murrysville, Pa. ] Appl. No. 879,732  Filed Nov. 25, 1969  Patented Sept. 7, I971 [73 l Assignee Westinghouse Air Brake Company Swissvale, Pa.
 HIGH SPEED RATE INDICATOR HAVING IMPROVED METERING CIRCUIT I Claim, 2 Drawing Figs.
 U.S.CI 324/78], 324/166, 324/105 [5 ll Int.Cl G0lr 23/02, GOlp 3/12,G0lr I 1/18  Field of Search 324/78 E, 78 I; 307/310, 253
 References Cited UNITED STATES PATENTS 2,965,769 12/1960 Bell 307/253 2,999,!68 9/l96l Henry 324/78 I UX FOREIGN PATENTS 958,060 5/1964 Great Britain 324/169 OTHER REFERENCES Bokstein; Industrial Electronics Measurement & control; Sept., l96l; Bobbs-Merrill Co., Inc. pp.75-79;
Gross; Radio-Electronics; Sept. 1965, pp. 54- 55 Primary ExaminerAlfred E. Smith Attorneys-ll. A. Williamson, A. G. Williamson, Jr. and .l. B.
Sotak ABSTRACT: This disclosure relates to a high rate parameter measuring system which uniquely allows extremely accurate rate measuring due to removal of indlication nonlinearity as well as the removal of inaccuracies due to reading over wide ranges of ambient temperatures which are intrinsic to the environment of said system. The system incorporates pulsesquaring circuitry which square incoming rate pulses indicative of said rate parameter, associatively coupled to monostable circuitry including an operational amplifier which monostable circuitry provides a constant pulse-width output, said pulse-width output, said monostable circuitry output electrically coupled to a metering circuit which produces a linear indication of the rate of said incoming rate pulses and includes a solid state semiconductive component which uniquely cooperates with the aforementioned components to provide the desired results.
Chashn Vblage lnzpedanae Mean HIGH SPEED RATE INDICATOR HAVING IMPROVED METERING CIRCUIT This invention relates to a high rate parameter measuring system.
More specifically, this. invention relates to a high rate parameter measuring system which incorporates a metering unit for providing flawless linear measurement of a high rate parameter due to nonreaction to temperature variations. The metering unit includes a low temperature drift switching component, a constant voltage supply, and an indication device. Thelow temperature drift switching component has a constant pulse-width input pulse trainand is electrically coupled to the constant voltage supply through theindication device and through a preselected reference node. The above-noted coupling provides for a relatively uniform current flow through the indication device whenever any of the constant width pulses appears at the input of the lowtemperature drift switching component.
In prior art arrangementsfor=measuring and indicating speed of moving objects, one main type of system employed with respect to measuringrates of incoming pulse trains which were rate parameters proportional to object speed, included transistor switching means witha grounded emitter electrode and a collector electrode connected to a time-averaging meter to provide an'indication of object speed.
This type ofspeed-measuring arrangement gave rise toiinaccuracy at substantially all frequencies developed due to relatively large temperature drifts in the transistor incorporated therein. Thesetemperaturednfts causedsubstantial variation in the collector to emitter saturation voltage V of the transistor; thus producing unreliable readings from the abovenoted time-averagingmeter.
The aforementionedand other disadvantages in prior art speed measuring and indication circuits being present, it is thereforedesirable to employ a speed indication system which substantially eliminates such disadvantages.
It is therefore an object of this invention to provide a novel high rate parameter-measuring system which is stable with respect to component temperature variation.
Anotherobject of this invention is to provide an improved high rateparameter-measuring system which provides a linear indication of the speed ofa moving object.
Still another object of this invention is to provide a new and improved high rate :parametenmeasuringsystem whichincorporates a'semiconductive devicewhich is relatively unaffected by temperature change'and insures rate indication accuracy overhigh rate frequency ranges;
In the attainment of the foregoingyobjects, the presentinvention incorporates a high rate parameter-measuring system including in combination pulse-squaring, means, monostable means; and metering means. The pulse-squaring meanshas an incoming rate signal indicative of a rate parameter and producesvan'output containing squared pulses corresponding to the incomingrate signal. The output of the-pulse-squaring means is electricallyiconnected to the monostable means. The monostable means is responsive to eachpulse of .the pulsesquaringmeansoutput to provide an output of constant-width pulses ata rate proportional to the above-notedrate parameter. The output of the monostable'means is electrically coupled to the abovementioned metering means. The metering means is responsive to the rate of the constant-width pulseson the output of the monostable means to provide'a linear indication which is proportional to the aforementioned rate parameter. Included in the meteringmeans is a low temperature drift switching means to'insure the linearity of the indication from the metering means. This is due to the fact that thelow temperature driftswitchingrneans is relatively unaffected by wide ranges of ambient temperatures whichmay be intrinsic to the environment of the system. Hence, relatively flawless measurement of the above-noted rate parameter. is achieved.
Other objects and advantages of the present invention will become apparent from the ensuing description of illustrative embodiments thereof, in the course of which reference is had to the accompanying drawings in which:
FIG. 1 sets forth a preferred embodiment of the high rate parameter measuring system of the present invention.
FIG. la shows a connection between the .low temperature drift switching means of thepreferred embodiment in FIG. 1 to the monostable means of the preferred embodiment of FIG. 1 which connection assures that the monostable means is relatively unaffected by wide temperature ranges.
Referring now to FIG. 1 and viewing a preferred embodiment of the high rate parameter measuring system of the present invention, it will be seen that a conventional-type pulse-squaring means 13 having an input 12 is electrically coupled to a monostable means .16 via lead 14. The monostable means 16 is conventionaland may be a Schmidt trigger which has an output 17' which is'electrically coupled to a metering means or unit 18. Particularly, the output 17 of the monostable means l6,is electrically connected to. a low temperature drift switching means 22, which in this preferred embodiment is a grounded collector NPN transistor having its .base electrode 33 coupled to output 17, its collector electrode34coupled to a constant voltage means 19 through groundor some preselected reference node, and its emitter electrode 36, coupled to an indication means 21. The constant voltage means 19 includes a resistor R supplied by a reference voltage 8+, and electrically coupled to a Zener diode 31 vialead 30;. The Zener diode 31 is also coupled to the-collector electrode 34 of the transistor 22 through ground. Boththe resistor R, and the Zener diode 31, which comprise constant voltage means18, are-electricallycoupled to the indication means 21 via lead 39. The indication means 21 includes an indication impedance means which in this preferred embodimentis a resistor R electrically coupled to an indication meter device 40. As shown, the low temperature drift switching means 22 is electrically coupled to the indication means 21 by the connection of emitter electrode36-to resistor R and the indication means 21 is electrically coupledto the constant voltage means 19 by the connection of indication meter device 40 to both resistor R and Zener diode 31 through lead 39.
Referring now to the operation of the high rate parameter system 1 of FIG. 1, it will be seen that a periodic waveform 11,
which waveform 11 is representative of a signal proportional to arate parameter such as the speed of a moving object is input to a conventional pulse-squaring means 13overlead 12. ltwill'be appreciated that while the waveform 11 appears sinusoidal, any periodic waveform indicative of the desired rateparameter may be incorporated in the present invention. The pulse-squaring means l3isdesignedto produce apulse foreach period of the periodic waveform input 11. An output waveform of square pulses 15 on-lead 'Mindicates the abovenoted pulse production. It-will be noted thatthe pulse-widths of the waveform 15 may vary in accordance with periodic frequency of the waveform 11 since the pulse-squaring meansv 13 is chosen to produce aleading pulse edge at a given positive threshold voltage with respect to periodic waveform 1'1 and atrailing pulse edgeatanother given voltage later on in time. Accordingly, the output squared-pulse waveform 15 of pulse-squaring'means 13 .isfed via lead14to a conventional.
monostable means 16, which .by the employment of conventional operational amplifiermeans, not shown, assures aconstant pulse-width output 16a on lead 17 for each incoming square pulse of waveform 15.
The constant pulse-width output isfed .to thelow tem: perature drift switchingmeans of metering means 18 which in thepresent embodiment is a transistor 22, and specifically to the base electrode 33 of transistor 22. Asstated previously,
thetransistor 22'has its collector electrode 34 grounded, while its emitter electrode 36 is electrically connected at a potential above groundjust the reverse of normal transistor intercircuit connection! The reason for the above-notedpresent'intercircuit connection of transistor 22 is that if with the normal type of transistor intercircuit connection, i.e., with emitter electrode 36 grounded and with collector electrode 34 connected at a potential above ground the collector-emittervoltage drop of transistor 22 at saturation, V would, as is well known, be relatively extremely susceptible to change with corresponding changes in transistor temperature. Accordingly, with different incoming pulses from lead 17, the resistor R would pass different nonuniform currents when temperature variants were involved and therefore the indication meter device 40 would provide inaccurate readings. Contrawise, the transistor 22 being connected as shown in FIG. 1, the emitter-collector voltage drop of transistor 22 at saturation, V is relatively unsusceptible to temperature variants. For example, as transistor temperature varies from C. to 100 C., V would correspondingly change on the order of 2 to l, but VECS would only decrease on the order of L1 to 1. Since a typical value of V is about 100 and a typical value of v is about 15,,,,,, it will be appreciated that far less error is incorporated by employing the present type of transistor intercircuit connection. Hence, with the resistance R and Zener diode 31 maintaining a constant voltage across the indication means 21 and transistor 22, there will be a substantially unifonn current flowing through R, whenever a pulse is present on lead 17 at base electrode 33 of transistor 22. The indication meter device 40 being a time-averaging d'arsonval meter, will average the above-noted uniform current pulses over a predetermined time period to provide an indication proportional to the above-noted rate parameter in accordance with the frequency of uniform current pulses flowing through resistor R This indication will be very accurate since the height of each pulse, namely, the current through R will 'be uniform for any pulse due to elimination of any effective overcome thereby advancing the state of the art.
Referring now to FIG. la, it is seen that an output 45 of metering means 18 is electrically coupled to monostable means 16. Specifically, output 45 is takenfrom the emitter electrode 36 of low temperature drift switching means, or transistor 22. Since, as described above, any current flowing from emitter electrode 36 of transistor 22 will be relatively unaffected by wide ranges to temperature, the output 45 to monostable means 16 will assure that monostable means 16 is also relatively unaffected by wide ranges of temperature and hence, increasetotal circuit integrity. In other words, the output present on line 45 may effectively in a conventional fashion be utilized in conjunction with the monostable means in a reference control function. It should, of course, be evident to those skilled in the art that there are a multitude of monostable devices available of the type referred to with reference to monostable means 16. In those monostable devices which have been designed with temperature change considerations taken into account this output 45 would not need to be employed.
Thus, it is apparent that the new and improved high rate parameter-measuring system of the present invention provides a more effective and electrically unique method for measuring and indicating the speed of an object by eliminating adverse effects of temperature variation and assuring indication linearity. 7
Having thus described my invention, whatl claim is:-; 1. This invention relates to a high rate parameter-measuring system, said system including pulse-squaring means, and monostable means, and metering means to measure said rate parameter and provide indications of a measured rate, said pulse-squaring means having an incoming rate signal indicative of said rate parameter and producing an output containing squared pulses corresponding to said incoming rate signal, said output of said pulse-squaring means associatively electrically coupled to said monostable means, said monostable means responsive to each pulse of said output of said pulse-squaring means to provide an output of constant-width pulses at a rate proportional to said rate parameter, said output of said monostable means electrically coupled to said metering means,
said metering means responsive to said rate of said constantwidth pulses from said monostable means to provide a linear indication proportional to said rate parameter,
said metering means including a low temperature drift switching means relatively unaffected by wide ranges of ambient temperatures which may be intrinsic to the environment of said system to insure said linearity of said indication from said metering means and thereby provide relatively flawless measurement of said high rate parameter,
said metering means further includes in combination said low temperature drift switching means which is a semiconductive device having an input which receives said output of constant-width pulses of said monostable means, and
constant voltage means, and
said low temperature drift switching means electrically coupled to said constant voltage means through said indication means and through a preselected reference node such that relatively constant current will flow through said indication means whenever one of said constantwidth pulses of said output of said monostable means appears at said input of said low temperature drift switching means,
said semiconductive device is a transistor having its base electrode electrically connected to said output of said monostable means to receive said constant-width pulses, its emitter electrode connected to said constant voltage means through said indication means, and its collector electrode connected to said constant voltage means through said reference node,
said constant voltage means includes a resistor impedance means and a Zener diode means, said impedance means supplied by a reference voltage and electrically coupled to said Zener diode means and said indication means, said Zener diode means also electrically coupled to said low temperature drift switching means through said preselected reference node, said constant voltage means providing a constant voltage across said low temperature drift switching means and said indication means.